Eyeglasses and/or prescription eyeglasses may include lenses assembled in a frame of the eyeglasses.
The lenses may have one or more optical parameters. The optical parameters of a lens may include, for example, a spherical power, a cylindrical power and/or a cylindrical axis.
Determining the spherical power, the cylindrical power, and/or the cylindrical axis of the lens may be useful, for example, if a user of the eyeglasses wishes to duplicate the eyeglasses and/or to produce spare lenses for the eyeglasses.